I've been looking on line for an answer to the following question and am hoping that someone here knows it. This US patent, granted in 1920 for an innertube with flange, was used for many years. Does anyone know when Dunhill ceased using it?
Time Frame For Dunhill Patent 1343253/20
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Pipephil seems to suggest that, although granted as a US patent for the flanged inner tube in 1920, it was stamped on pipes from 1927-1933 and the again from 1937 - 1941 (though in the latter case without the words inner tube also stamped - that ceased 1n 1935):
http://www.pipephil.eu/logos/en/dunhill/patent2.html#349
http://www.pipephil.eu/logos/en/dunhill/patent2.html#349
Hi guys! Thank you for your help. Dunhill continued to use inner tubes for many years and may still do so, as far as I know. It's not the inner tube, it's the duration of the patent and the timeframe for the actual use of this particular patent stamp that I'm trying to determine.
I've seen the pipephil timeline and I'm looking for any corroboration from other sources.
I've seen the pipephil timeline and I'm looking for any corroboration from other sources.
Hi rothnh,
Not a bad idea. I did look at the actual patent application. You can find it using Google patents, but could not see where it listed a period of duration. For example, the Barling stem and bit patent stipulates 14 years. I couldn't spot any such stipulation on the Dunhill patent, which was granted 16 years earlier than the Barling one. Patent law changes and has different rules for different items. There's no "one size fits all".
Not a bad idea. I did look at the actual patent application. You can find it using Google patents, but could not see where it listed a period of duration. For example, the Barling stem and bit patent stipulates 14 years. I couldn't spot any such stipulation on the Dunhill patent, which was granted 16 years earlier than the Barling one. Patent law changes and has different rules for different items. There's no "one size fits all".
Nor am I, but I promised a friend that I would help him out with this question. He's technologically phobic to an alarming degree. Currently I'm on the US Patent Office's Documents site, watching the little wheel spin while supposedly retrieving specifications. Boring.
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